PURPOSE: To demonstrate the circular vortex.
DESCRIPTION: Place the lit candle on its holder about six feet in front of the opening. Tapping the elastic drumhead on the back of the box pushes air out of the hole. The geometry of the hole causes the air to assume the configuration of a rotating donut shape, like a smoke ring. The vortex travels rapidly through the air and blows out the candle.
SUGGESTIONS: Before you do this experiment, you might blow air onto your students. They are quite amazed that the flow readily blows their hair.
REFERENCES: (PIRA 2C50.12)
EQUIPMENT: Vortex box and candle with holder.
SETUP TIME: None.
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